1. Field of the Invention
The present invention relates to devices and methods of controlling and signal processing for vibratory gyroscopes.
2. Description of the Related Art
Vibratory rate gyroscopes exploit a coriolis term in the equations of motion to link two modes of the sensor's elastic structure. One mode is driven to a constant-amplitude harmonic response (requiring a control loop) and consequently any angular motion about the sensor's sensitive axis causes the other mode to respond to this rotation. The amplitude of this response is related to the angular rotation rate. A second feedback loop, as described by Challoner, et. al U.S. Pat. No. 6,360,601 can be used to regulate the response of the second mode to zero and in this case the feedback signal contains information on the angular rotation rate that may be calculated by demodulating this signal with the driven mode's response. Implementation of the feedback control and signal processing electronics for vibratory gyroscopes has previously required custom architectures and solutions.
The feedback control and signal processing elements are present in existing vibratory gyros in the form of a discrete analog implementation and/or a general purpose centralized digital signal processing (DSP) chip. The disadvantage of a discrete analog implementation is its inflexibility with regard to modifying component values for the purpose of “tuning” or customizing the control loops for a given sensor. Since mass-produced sensors will have some degree of variability amongst a batch of supposedly identical devices, this inflexibility represents a significant drawback. On the other hand, one disadvantage of using a general purpose digital signal processing chip is that general purpose centralized DSPs do not lend themselves to applications in which low power consumption is necessary (e.g., spacecraft, mobile systems, etc.).
There is a need for devices and methods for controlling and signal processing for vibratory gyroscopes which are flexible and adaptable to various vibratory gyro sensors. Further, there is a need for such devices and methods which allow easily customized control loops for such sensors. Finally, there is also a need for such devices and methods which operate at low power consumption levels. The present invention meets all these needs.